1. Technical Field
The inventive arrangements relate generally to methods and apparatus providing advanced operating features for audio only, video only and both video and audio programs recorded on disk media, for example recordable digital video disks, hard drives and magneto optical disks.
2. Description of the Related Art
Various devices have been developed to enable consumers to record video and/or audio programs for later presentation. Such devices include tape recorders, video cassette recorders, recordable compact discs, and most recently, recordable digital video discs (DVD). Hard drives and magneto optical discs have also been used.
A DVD that can be recorded on only once, and thereafter is essentially a DVD read only memory, is referred to by the acronym DVD-R. The acronym DVD-R is also used generally to refer to the write-once, or record-once, technology. Several formats are available for DVD's to be recorded on, erased and re-recorded; that is, overwritten or rewritten. These are referred to by the acronyms DVD-RAM, DVD-RW and DVD+RW. As of this time no uniform industry standard has been adopted. The acronyms DVD-RAM, DVD-RW and DVD+RW are also used generally to refer to the respective rewritable technologies. Reference herein to rewritable DVD technology, devices and methods is generally intended to encompass all of the standards which are now being used, as well as those which may be developed in the future.
Although rewritable DVD technology is generally available, operation is limited to such basic functions as play, record, fast forward reverse and stop. Pause is available, but only as a counterpart to pause operation in a VCR, for example interrupting the play back of a prerecorded program or interrupting the recording of a viewed program to eliminate commercials from the recording. Unlike computer hard drives, recordable DVD devices have a very significant additional function, which is playing back prerecorded DVD's. Thus, there is an economic incentive to develop rewritable DVD technology, including methods and devices, that can be used instead of a computer hard drive. It is a challenge to provide such devices with improved, advantageous features without compromising the goal of decreasing costs and increasing sales.
A number of new features for rewritable disk media, for example DVD, include pause, catch-up and instant replay. These features require apparently simultaneous reading and writing. These features require that operation of the write buffer (also referred to as the record buffer) and the read buffer (also referred to as the track or play buffer) be optimized to avoid write buffer overflow read buffer underflow. Write buffer overflow results in a loss of program material after encoding and before writing onto the disk. Read buffer underflow results in an interruption of the program material as it is being played back. Catch-up modes, play-skip modes and smooth-catch-up modes or combinations of them all require such buffer optimization.
Pause, instant replay, catch-up, and all other trick modes are good features for DVD recorders, such as DVD-RW, DVD-RAM, DVD+RW just name a few. Here, pause is used to pause a broadcast TV program. Instant replay allows people to watch the recording instantly. Catch-up allows people to catch up the program after unpause or other implementations of trick modes. Trick modes include fast reverse, slow reverse, fast forward, slow forward, skip, and jump. All these features are very hard to implement on a DVD recorder for simultaneous encoding and decoding. It not only requires a fast front-end, but also needs a good strategy to manipulate the buffers in order to do seamless playback without loss of any data.